1. Field of the Invention
The present invention relates to a moving status detecting apparatus for detecting the moving status of a movable member or the like arranged to operate for image blur correction.
2. Related Background Art
In present cameras, all important operations for photography including determination of exposure, focusing, and so on are automated, and thus the possibility of mistake photography is very little even in the case of people unfamiliar with manipulation of a camera.
Further, systems for preventing hand shakes from affecting the camera have been also investigated these years and there is thus little factor to induce mistake photography of photographer.
Now described briefly is a system for preventing a camera shake due to hand shakes.
The hand shakes exerted on the camera upon photography are normally the vibration of frequencies ranging from 1 Hz to 12 Hz, and a fundamental idea for enabling to take blurpree photographs even with occurrence of such hand shakes at the time of shutter release is to detect vibration of camera due to the above hand shakes and to displace a correction lens according to a detected value thereof. Accordingly, in order to achieve the capability of taking blurfree photographs even with occurrence of vibration of camera, it is necessary first to detect the vibration of camera accurately and second to correct a change of the optical axis due to the hand shake.
This detection of vibration (camera vibration) can be carried out, theoretically speaking, by providing the camera with vibration detecting means for detecting angular acceleration, angular velocity, angular displacement, or the like and camera deviation detecting means for electrically or mechanically integrating an output signal from the sensor to output a signal of angular displacement. Then an image blur can be suppressed by driving a correction optical device for moving the photographic optic axis radially based on information of this detection.
Here, a blur correction system using the vibration detecting means will be outlined referring to FIG. 57.
The example of FIG. 57 is a drawing of a system for suppressing image blurs resulting from pitch or vertical deviation 10081p and yaw or horizontal deviation 10081y of camera in the directions of arrows 10081 illustrated therein.
In the same drawing, reference numeral 10082 designates a lens barrel, and each of 10083p and 10083y vibration detecting means for detecting pitching of camera or yawing of camera, respectively, a vibration detection direction of which is represented by 10084p, 10084y, respectively. Numeral 10085 denotes a correction optical device (wherein 10086p, 10086y are coils each for giving thrust to the correction optical device 10085 and wherein 10089p, 10089y are position detecting elements each for detecting the position of the correction device 10085), and the correction optical device 10085 is provided with a position control loop and is driven using outputs from the vibration detecting means 10083p, 10083y as target values, thus assuring stability on the image plane 10088.
FIG. 58 is an exploded perspective view to show the structure of the correction optical device (the details of which will be described hereinafter, but which is comprised of correction means and means for supporting and engaging the correction means) suitably applicable for such an object. This structure will be described as also referring to FIG. 59 to FIG. 67.
Back projecting lugs 10071a (three lugs one of which is on the blind side) of base plate 10071 (an enlarged view of which is illustrated in FIG. 61) fit the unrepresented lens barrel and well-known rollers of barrel or the like are screwed to corresponding holes 10071b, whereby the base plate is fixed to the barrel.
A second yoke 10072 with bright plating, made of a magnetic member, is screwed to holes 10071c of base plate 10071 with screws penetrating holes 10072a. Further, permanent magnets (shifting magnets) 10073 such as neodymium magnets magnetically adhere to the second yoke 10072. The magnetization direction of each permanent magnet 10073 is the direction of each arrow 10073a illustrated in FIG. 58.
Coils 10076p, 10076y (shifting coils) are snap-fit in and bonded to (i.e., the coils are forced into and bonded to) a support frame 10075 (an enlarged view of which is illustrated in FIG. 62) to which a correction lens 10074 is fixed by C-ring or the like (FIG. 62 shows the support frame without the coils). Further, light emitting elements 10077p, 10077y such as IREDs are also bonded to the back of the support frame 10075 and light emitted therefrom travels through slit 10075ap, 10075ay into an associated position detecting element 10078p, 10078y such as a PSD described below.
Support balls 10079a, 10079b with a spherical tip of POM (polyacetal resin) or the like and a charge spring 10710 are inserted in each of holes 10075b (at three positions) of the support frame 10075 (also see FIG. 59 and FIG. 60A) and the support ball 10079a is thermally caulked to the support frame 10075 to be fixed therein (so that the support ball 10079b can slide in the extending direction of hole 10075b against spring force of charge spring 10710.
FIG. 59 is a lateral cross-sectional view of the correction optical device after assembled. The support ball 10079b, charge spring 10710 charged, and support ball 10079a are inserted in this order in the direction of arrow 10079c into the hole 10075b of support frame 10075 (wherein the support balls 10079a, 10079b are components of the same configuration) and the peripheral edge 10075c of hole 10075b is thermally caulked finally to prevent the support ball 10079a from slipping out therefrom.
A cross section of hole 10075b along the direction perpendicular to FIG. 61 is illustrated in FIG. 60A and a plan view obtained when the cross-sectional view of FIG. 60A is observed along the direction of arrow 10079c is illustrated in FIG. 60B. Depths of regions represented by symbols A to D in FIG. 60B are indicated by A to D in FIG. 60A.
Since the rear ends of wings 10079aa of the support ball 10079a are received and regulated by the range of the surface of depth A, the support ball 10079a is fixed to the support frame 10075 by thermal caulking of the peripheral edge 10075a.
Since the tip ends of wings 10079ba of the support ball 10079b are received by the range of surface of depth B, the support ball 10079b will never out in the direction of arrow 10079c from the hole 10075b because of the charged spring force of the charge spring 10710.
Since the support ball 10079b is received by the second yoke 10072 as shown in FIG. 59 after completion of assembly of the correction optical device, it will not slip out of the support frame 10075, of course, but the surface B of the slip-out preventing range is provided in consideration of assemblability.
The shape of hole 10075b of support frame 10075 shown in FIG. 59 and FIGS. 60A and 60B can be molded with simple two-divided molds one of which is arranged to slide in the opposite direction to the arrow 10079c without requiring a complex-internal-diameter slide mold in the case of molding the support frame 10075, whereby the dimensional accuracy can be set more precisely by that degree.
Since the support balls 10079a, 10079b are the same components as described, component costs are lowered, an assembling error can be avoided, and it is also advantageous in management of components.
For example, fluorine-based grease is applied to a bearing part 10075d of the above support frame 10075, and L-shaped shaft 10711 (of non-magnetic stainless steel material) is inserted thereinto (see FIG. 58). The other end of the L-shaped shaft 1011 is inserted into a bearing part 10071d (similarly coated with grease) formed in the base plate 10071, and the support frame 10075 is set in the base plate 10071 as putting the support balls 10079b together at the three positions on the second yoke 10072.
Next, positioning holes 10712a (at three positions) of first yoke 10712 shown in FIG. 58 are made to engage with pins 10071f (at three positions) of the base plate 10071 shown in FIG. 61 and the first yoke 10712 is received by receiving surfaces 10071e (at five positions) also shown in FIG. 61 to be magnetically coupled with the base plate 10071 (by the magnetic force of permanent magnets 10073).
This makes the back of first yoke 10712 contact the support balls 10079a and the support frame 10075 is sandwiched between the first yoke 10712 and the second yoke 10072 to be positioned in the directions along the optical axis.
Contact surfaces between the support balls 10079a, 10079b and the first yoke 10712 or the second yoke 10072 are also coated with the fluorine-based grease and the support frame 10075 is free to slide in the plane perpendicular to the optical axis with respect to the base plate 10071.
The above L-shaped shaft 10711 supports the support frame 10075 so that it can slide only in the directions of arrows 10713p, 10713y with respect to the base plate 10071, which regulates relative rotation (rolling) of the support frame 10075 about the optical axis with respect to the base plate 10071.
A large engagement play is given in the optic-axis directions between the L-shaped shaft 10711 and the bearing parts 10071d, 10075d, which prevents double engagement against the regulation in the optic-axis directions effected by the sandwich arrangement of the support balls 10079a, 10079b between the first yoke 10712 and the second yoke 10072.
The surface of the first yoke 10712 is covered by an insulating sheet 10714, and a hard board 10715 having plural ICs (ICs for amplifying outputs from the position detecting elements 10078p, 10078y, ICs for driving the coils 10076p, 10076y, etc.) is screwed thereonto by engaging positioning holes 10715a (at two positions) with pins 10071h (at two positions) of the base plate 10071 shown in FIG. 61 and inserting screws through the holes 10715b and the holes 10712b of the first yoke 10712 into the holes 10071g of the base plate 10071.
Here, the position detecting elements 10078p, 10078y are positioned on the hard board 10715 by a tool and are soldered thereto, and a flexible board 10716 for transmission of signal is also bonded by thermo-compression bonding to the back of hard board 10715 in the range 10715c (see FIG. 58) surrounded by the dashed line.
From the flexible board 10716 a pair of arms 10716bp, 10716by extend in directions on the plane perpendicular to the optical axis to be hooked on hooking parts 10075ep, 10075ey (see FIG. 62) of the support frame 10075, respectively. Terminals of the light emitting elements 10077p, 10077y and terminals of coils 10076p, 10076y are soldered to the arms.
By this, drive of the light emitting elements 10077p, 10077y, such as the IREDs, and the coils 10076p, 10076y is carried out with intervention of the flexible board 10716 from the hard board 10715.
The arms 10716bp, 10716by (see FIG. 58) of the flexible board 10716 have respective bending parts 10716cp, 10716cy, and elasticity of the bending parts decreases loads of the arms 10716bp, 10716by on rotation of the support frame 10075 in the plane perpendicular to the optical axis.
The first yoke 10712 has projecting faces 10712c formed by die cutting, and the projecting faces 10712c penetrate associated holes 10714a of the insulating sheet 10714 to be in direct contact with the hard board 10715. An earth (GND: ground) pattern is formed on this contact surface on the hard board 10715 side. When the hard board 10715 is screwed to the base plate, the first yoke 10712 is earthed to be an antenna, thereby being prevented from giving noise to the hard board 10715.
A mask 10717 shown in FIG. 58 is positioned against pins 10071h of the base plate 10071 and is fixed by a double-adhesive tape on the hard board 10715.
The base plate 10071 has a through hole 10071i (see FIG. 58 and FIG. 61) for permanent magnet, through which the back of the second yoke 10072 is exposed. A permanent magnet 10718 (locking magnet) is set in this through hole 10071i to be magnetically coupled with the second yoke 10072 (see FIG. 59).
A coil 10720 (locking coil) is bonded to a lock ring 10719 (see FIG. 58, FIG. 59, and FIG. 63) and a bearing 10719b (see FIG. 64) is provided on the back of lug 10719a of the lock ring 10719. An armature pin 10721 is put through an armature rubber 10722 (see FIG. 58), the armature pin 10721 is set through the bearing 10719b, thereafter an armature spring 10723 is set around the armature pin 10721, and it is fit into an armature 10724 to be fixed by caulking.
Accordingly, the armature 10724 can slide in the directions of arrows 10725 relative to the lock ring 10719 against the charge force of armature spring 10723.
FIG. 64 is a plan view obtained when the correction optical device after completion of assembly is observed from the back side of FIG. 58. In this figure, the lock ring 10719 is pushed into the base plate 10071 as outer peripheral notches 10719c (at three positions) of the lock ring 10719 are aligned with corresponding internal peripheral projections 10071j (at three positions) of the base plate 10071, and thereafter the lock ring is rotated clockwise to effect well-known bayonet coupling for preventing slip-out, whereby the lock ring 10719 is attached to the base plate 10071.
Therefore, the lock ring 10719 can rotate about the optical axis with respect to the base plate 10071. However, in order to prevent the bayonet coupling from being disengaged when the lock ring 10719 rotates so as to return the notches 10719c into the same phase as the projections 10071j, a lock rubber 10726 (see FIG. 58 and FIG. 64) is pressed into the base plate 10071 to regulate rotation of the lock ring 10719 so that the lock ring 10719 can rotate only by an angle .theta. (see FIG. 64) of notch part 10719d up to the position where it is regulated by the lock rubber 10726.
A permanent magnet 10718 (locking magnet) is also attached to a locking yoke 10727 (see FIG. 58) of magnetic member, and holes 10727a (at two positions) thereof are engaged with the pins 10071k (see FIG. 64) of the base plate 10071. Then holes 10727b (at two positions) and 10071n (at two positions) are coupled by screwing.
The permanent magnet 10718 on the base plate 10071 side, the permanent magnet 10718 on the locking yoke 10727 side, the second yoke 10072, and the locking yoke 10727 form a well-known closed magnetic circuit.
The locking rubber 10726 is prevented from slipping out when the lock yoke 10727 is screwed. The lock yoke 10727 is not illustrated in FIG. 64 for the sake of above description.
A lock spring 10728 is stretched between hook 10719e of the lock ring 10719 and hook 10071m of the base plate 10071 (see FIG. 64), so as to bias the lock ring 10719 clockwise. An adhesion coil 10730 is inserted into an adhesion yoke 10729 (see FIG. 58 and FIG. 64) to be screwed through a hole 10729a of the base plate 10071.
The terminals of coil 10720 and the terminals of adhesion coil 10730 are, for example, of the twisted pair configuration of four-stranded polyester-coated wires and are soldered to trunk 10716d of the flexible board 10716.
The mechanical part of the correction optical device as described above is roughly composed of three elements, i.e., correction means for moving the optical axis radially, support means for supporting the correction means, and engagement means for engaging the correction means.
The correction means is made up of the lens 10074, support frame 10075, coils 10076p, 10076y, IREDs 10077p, 10077y, position detecting elements 10078p, 10078y, ICs 10731p, 10731y, support balls 10079a, 10079y, charge spring 10710, and support shaft 10711. The support means is made up of the base plate 10071, second yoke 10072, permanent magnets 10073, and first yoke 10712. Further, the engagement means is made up of the permanent magnets 10718, lock ring 10719, coil 10720, armature shaft 10721, armature rubber 10722, armature spring 10723, armature 10724, lock rubber 10726, yoke 10727, lock spring 10728, adhesion yoke 10729, and adhesion coil 10730.
Among the configuration of the correction means, the lens 10074 and support frame 10075 compose a correction optical system, the PSDs 10078p, 10079y, ICs 10731p, 10731y, and IREDs 10077p, 10077y compose position detecting means, and the coils 10076p, 10076y, second yoke 10072, permanent magnets 10073, and first yoke 10712 compose driving means. Namely, the correction means is mainly composed of the constituents of the correction optical system, position detecting means, and driving means for driving the correction optical system.
Then the correction optical device, the vibration detecting means (see FIG. 57), and the like constitute a blur correction system (blur correction device).
The ICs 10731p, 10731y on the hard board 10715 are ICs for amplifying an output from each position detecting element 10078p, 10078y and the internal configuration of each IC is as shown in FIG. 65. (Since the ICs 10731p, 10731y have the same configuration, only 10731p is shown herein.)
In FIG. 65, current-voltage converting amplifiers 10731ap, 10731bp convert photocurrents 10078i.sub.1 p, 10078i.sub.2 p generated in the position detecting element 10078p (comprised of resistors R1, R2) by the light emitting element 10077p to respective voltages and a differential amplifier 10731cp obtains and amplifies a difference between outputs of respective current-voltage converting amplifiers 10731ap, 10731bp.
The light emitted from the light emitting element 10077p, 10077y is incident, as described previously, through the slit 10075ap, 10075ay onto the position detecting element 10078p, 10078y, but movement of the support frame 10075 in the plane normal to the optic axis will change the position of incidence onto the position detecting element 10078p, 10078y.
The position detecting element 10078p has sensitivity in the directions of arrows 10078ap (see FIG. 58) and the slit 10075ap is so shaped as to broaden a beam in the directions (in the directions 10078ay) perpendicular to the arrows 10078ap and as to narrow the beam in the directions of arrows 10078ap. Therefore, only when the support frame 10075 moves in the direction along the arrow 10713p, the balance between the photocurrents 10078i.sub.1 p, 10078i.sub.2 p of the position detecting element 10078p changes, and the differential amplifier 10731cp gives an output according to the movement of the support frame 10075 in the direction along the arrow 10713p.
Further, the position detecting element 10078y has detection sensitivity in the directions of arrows 10078ay (see FIG. 58) and the slit 10075ay is shaped to extend in the directions (in the directions 10078ap) perpendicular to the arrows 10078ay. Therefore, only when the support frame 10075 moves in the direction along the arrow 10713y, the position detecting element 10078y changes its output.
A summing amplifier 10731dp obtains the sum of outputs from the current-voltage converting amplifiers 10731ap, 10731bp (the sum of receiving light quantity of the position detecting element 10078p) and a driving amplifier 10731ep receiving this signal drives the light emitting element 10077p in accordance therewith.
Since the above light emitting element 10077p changes its emitting light quantity very unstably depending upon the temperature or the like, the absolute quantity (10078i.sub.1 p+10078i.sub.2 p) of the photocurrents 10078i.sub.1 p, 10078i.sub.2 p of the position detecting element 10078p varies in accordance therewith. This also changes the output from the differential amplifier 10731cp which is (10078i.sub.1 p-10078-i.sub.2 p) indicating the position of the support frame 10075.
However, if the light emitting element 10077p is controlled by the aforementioned driving circuit so as to keep the sum of receiving light quantity constant as described above, the output from the differential amplifier 10731cp will not change.
The coils 10076p, 10076y shown in FIG. 58 are located in the closed magnetic circuit made up by the permanent magnets 10073, first yoke 10712, and second yoke 10072. When electric current is made to flow in the coil 10076p, the support frame 10075 is thus driven in the directions of arrows 10713p (the well-known Fleming's left-hand rule). When electric current is made to flow in the coil 10076y, the support frame 10075 is driven in the directions of arrows 10713y.
In general, the configuration is such that the output from the position detecting element 10078p, 10078y is amplified by IC 10731p, 10731y, the coil 10076p, 10076y is driven with the output, and the support frame 10075 is driven thereby to change the output from the position detecting element 10078p, 10078y.
When the driving direction (polarity) of coil 10076p, 10076y is set to the direction to decrease the output of position detecting element 10078p, 10078y (negative feedback), driving force of the coil 10076p, 10076y stabilizes the support frame 10075 at a position where the output of position detecting element 10078p, 10078y becomes almost zero.
This technique of drive with negative feedback of position detection output is called a position control technique, whereby, for example, when a target value (for example, a signal of hand shake angle) is introduced from the outside into the IC 10731p, 10731y, the support frame 10075 is driven very loyally according to the target value.
In practice, the output from the differential amplifier 10731cp, 10731cy is sent via the flexible board 10716 to the main board not illustrated to be subjected to analog-digital conversion (A/D conversion) therein and to be taken into a microcomputer.
In the microcomputer the signal is compared with the target value (the signal of hand shake angle) and is amplified as occasion demands, and then the signal is subjected to phase lead compensation by the well-known digital filtering technique (for stabilizing the position control more). After that, the signal is guided again through the flexible board 10716 into the IC 10732 (for driving the coils 10076p, 10076y). The IC 10732 performs the well-known PWM (Pulse-Width Modulation) of the coils 10076p, 10076y based on the input signal, thereby driving the support frame 10075.
The support frame 10075 can slide in the directions of arrows 10713p, 10713y as described previously and the position thereof is stabilized by the position control technique described above. However, in the case of consumer-oriented optical devices such as cameras, always controlling the support frame 10075 is not allowed from the viewpoint for preventing consumption of power supply.
Since in a non-controlled state the support frame 10075 becomes freely movable in the plane perpendicular to the optic axis, a countermeasure is necessary against damage or occurrence of colliding sound at stroke edges thereof in that case.
Three radially projecting protrusions 10075f are provided on the back of support frame 10075 as shown in FIG. 62 and FIG. 64 and the tips of the protrusions 10075f engage the internal peripheral surface 10719g of the lock ring 10719 as shown in FIG. 64. Accordingly, the support frame 10075 is restrained relative to the base plate 10071 in the all directions.
FIGS. 66A and 66B are plan views to show the relationship of operation between the lock ring 10719 and the support frame 10075, which are drawings obtained by extracting only the main part from the plan view of FIG. 64. For facilitating understanding of description, the layout is changed sightly from the actually assembled state. Further, cam portions 10719f (at three positions) of FIG. 66A are not provided throughout the entire region in the generatrix direction of the cylinder of lock ring 10719, as shown in FIG. 59 and FIG. 63, so that they are not seen actually along the viewing direction of FIGS. 66A, 66B. However, they are illustrated therein for the sake of explanation.
As shown in FIG. 59, the coil 10720 (10720a represents four-stranded leader wires guided along the outer periphery of lock ring 10719 by an unrepresented flexible board or the like and connected to the terminals 10716e on the trunk 10716d of the flexible board 10716 via the terminals 10719h) is in the closed magnetic circuit between the permanent magnets 10718 and generates torque to rotate the lock ring about the optical axis with supply of electric current to the coil 10720.
This drive of coil 10720 is also controlled by a command signal supplied from the unrepresented microcomputer through the flexible board 10716 to the driving IC 10733 on the hard board 10715, and the IC 10733 PWM-drives the coil 10720.
In FIG. 66A, the winding direction of coil 10720 is set so as to generate counterclockwise torque in the lock ring 10719 with energization of coil 10720, so that the lock ring 10719 rotates counterclockwise against the spring force of the lock spring 10728.
The lock ring 10719 is stable before energization of coil 10720 as being kept in contact with the lock rubber 10726 by the force of lock spring 10728.
With rotation of the lock ring 10719, the armature 10724 comes to contact the adhesion yoke 10729 and to contract the armature spring 10723, thereby equalizing the positional relation between the adhesion yoke 10729 and the armature 10724. Thus, the lock ring 10719 stops rotation as shown in FIG. 66B.
FIG. 67 is a timing chart of the drive of lock ring.
When the coil 10720 is energized (PWM-driven as indicated by 10720b) at arrow 10719i of FIG. 67, the adhesion magnet 10730 is also energized at the same time (10730a). Therefore, the armature 10724 comes to contact the adhesion yoke 10729 and then the armature 10724 comes to adhere to the adhesion yoke 10729 at the equalized point of time.
Next, when the energization of coil 10720 is stopped at the point of time indicated by 10720c of FIG. 67, the lock ring 10719 becomes ready for clockwise rotation because of the force of lock spring 10728. However, since the armature 10724 adheres to the adhesion yoke 10729 as described above, the rotation is restricted. At this time, the projections 10075f of the support frame 10075 are located at positions opposed to the associated cam portions 10719f (because the cam portions 10719f are rotated up to the positions). Therefore, the support frame 10075 becomes capable of moving by a clearance between the projections 10075f and the cam portions 10719f.
This allows the support frame 10075 to drop in the direction of gravity G (see FIG. 66B), but no drop occurs because the support frame 10075 is also brought into the controlled state at the point of arrow 10719i of FIG. 67.
In the non-controlled state the support frame 10075 is restrained by the internal periphery of the lock ring 10719, but in practice it has a play equivalent to an engagement play between the projection 10075f and the internal peripheral wall 10719g. Namely, the support frame 10075 drops by this play in the direction of gravity G, so that there is deviation between the center of support frame 10075 and the center of base plate 10071.
Because of it, control is carried out in such a manner that the center of support frame is moved toward the center of base plate 10071 (the optic center) slowly, for example, for one second from the point of arrow 10719i.
This is because quick movement to the center would cause a photographer to sense fluctuation of image through the correction lens 10074 and to have unpleasant feeling and because an image can be prevented from being degraded due to the movement of support frame 10075 even with exposure carried out during this period. (For example, the support frame is moved 5 .mu.m every one eighth second.)
Specifically, the outputs from the position detecting elements 10078p, 10078y are stored at the point of arrow 10719i of FIG. 67, control of the support frame 10075 is started using the output values as target values, and the support frame is moved toward the target values at the optic center preliminarily set, for one second after that (see 10075g in FIG. 67).
After the lock ring 10719 is rotated (unlocked), the support frame 10075 is driven based on the target values from the vibration detecting means (as overlapping with the moving operation of the support frame 10075 to the center position as described above), thus starting blur correction.
When blur correction off is activated at the point of arrow 10719j in order to end the blur correction, the target values from the vibration detecting means stop being supplied to the correction driving means for driving the correction means, thereby stopping the support frame 10075 as controlled at the center position. At this time the power to the adhesion coil 10730 is stopped (10730b). Then the adhesive force of the armature 10724 due to the adhesion yoke 10729 disappears, so that the lock ring 10719 is rotated clockwise by the lock spring 10728, returning to the state of FIG. 66A. Since at this time the lock ring 10719 is restrained from rotating by contact with the lock rubber 10726, the colliding sound of the lock ring 10719 at the end of rotation can be suppressed to a low level.
After that (for example, after a lapse of 20 msec), control to the correction driving means is interrupted to end the timing chart of FIG. 67.
FIG. 68, composed of FIGS. 68A and 68B, and FIG. 69 are block diagrams to show the outline of the blur correction system.
In these diagrams, reference numeral 10091 designates vibration detecting means corresponding to the vibration detecting means 10083p, 10083y of FIG. 67, which is composed of a deviation detecting sensor for detecting angular velocity, such as a vibration gyro, and sensor output calculating means for cutting the DC component of an output from the deviation detecting sensor and for integrating it to obtain angular displacement.
The angular displacement signal from this vibration detecting means 10091 is supplied to target value setting means 10092. This target value setting means 10092 is composed of a variable differential amplifier 10092a and a sample-hold circuit 10092b, as shown in FIGS. 68A and 68B. Since the sample-hold circuit 10092b is always in sample, two input signals into the variable differential amplifier 10092a are always equal and an output thereof is zero. However, when the sample-hold circuit 10092b is changed into a hold state by an output from delay means 10093 described below, the variable differential amplifier 10092a starts continuous output, taking zero at that point.
The amplification factor of the variable differential amplifier 10092a can be varied by output of blur correction sensitivity setting means 10094. The reason of this variable arrangement is as follows. A target value signal of the target value setting means 10092 is a target value (command signal) for correction means 10910 to follow up, and a correction amount of the image plane to a drive amount of the correction means 10910 (i.e., blur correction sensitivity) changes depending upon optical characteristics based on focus change upon zooming, focusing, or the like. Therefore, the variable configuration of amplification is for compensating for the change of blur correction sensitivity.
Therefore, the blur correction sensitivity setting means 10094 receives, as shown in FIGS. 68A and 68B, zooming focal-length information from zoom information output means 10095 and focusing focal-length information based on distance-measurement information of exposure preparation means 10096, and calculates the blur correction sensitivity based on the information or extracts blur correction sensitivity information preliminarily set, based on the information, thereby changing the amplification factor of the variable differential amplifier 10092a in the target value setting means 10092.
The correction drive means 10097 corresponds to the ICs 10731p, 10731y, 10732 mounted on the hard board 10715 of FIG. 58 and the target value from the target value setting means 10092 is supplied as a command signal to the correction drive means 10097.
Correction activation means 10098 is a switch for controlling connection of coils 10086p, 10086y provided in the correction means 10910 with the IC 10732 on the hard board 10715 of FIG. 58. As shown in FIG. 69, both terminals of each coil 10076p, 10076y are normally short-circuited by connecting the switch 10098a with the terminal 10098c. With an input signal from AND means 10099 the switch 10098a is connected to terminal 10098b to change the correction means 10910 into the control state (in which the blur correction is not started yet, but power is supplied to the coils 10076p, 10076y to stabilize the correction means 10910 at the position where the signals from the position detecting elements 10084p, 10084y, become almost zero). At the same time as it the output signal of AND means 10099 is also supplied to engaging means 10914, whereby the engaging means 10914 releases engagement of the correction means 10910.
The correction means 10910 supplies the position signals of position detecting elements 10084p, 10084y to the correction drive means 10097 to perform the position control as described above.
When the AND means 10099 receives inputs of two signals, a release half-depression signal SW1 of release means 10911 and an output signal from blur correction changeover means 10912, AND gate 10099a (see FIGS. 68A and 68B), which is a component of the AND means, outputs a signal. Namely, when the photographer turns on a blur correction switch of blur correction changeover means 10912 and when the photographer half depresses the release means 10911, the correction means 10910 is disengaged to go into the control state.
The SW1 signal of release means 10911 is also supplied to the exposure preparation means 10096, as shown in FIGS. 68A and 68B, and the exposure preparation means 10096 performs photometry, distance measurement, and lens focusing drive. Focusing information obtained here is supplied to the blur correction sensitivity setting means 10094.
The delay means 10093 receives an output signal from the AND means 10099 and outputs it, for example, one second after, thereby making the target value setting means 10092 output the target value signal as described above.
Although not illustrated, the vibration detecting means 10091 also starts in synchronism with the SW1 signal of the release means 10911. As described previously, an arithmetic of output from a sensor including a large time constant circuit such as an integrator requires a certain time before the output becomes stabilized.
The delay means 10093 functions to wait for stabilization of output from the vibration detecting means 10091 and thereafter to make the target value signal output to the correction means 10910, thus achieving the configuration to start the blur correction after the output from the vibration detecting means 10091 becomes stabilized.
Exposure means 10913 moves the mirror up with input of a release full-depression SW2 signal from the release means 10911, opens and closes the shutter at a shutter speed obtained based on a photometric value of the exposure preparation means 10096 to effect exposure, and then moves the mirror down, thus ending photography.
When after end of photography the photographer takes the finger away from the release means 10911 to turn the SW1 signal off, the AND means 10099 stops its output, the sample-hold circuit 10092b of the target value setting means 10092 goes into the sampling state, and the output from the variable differential amplifier 10092a becomes zero. Accordingly, the correction means 10910 returns into the control state with stopping correction drive.
Since the output of AND means 10099 becomes off, the engaging means 10914 engages the correction means 10910 and thereafter the switch 10098a of the correction activation means 10098 is connected to the terminal 10098c, thereby making the correction means 10910 non-controlled.
The vibration detecting means 10091 continues its operation, by a non-illustrated timer, for a certain period of time (for example, for five seconds) after stop of manipulation of the release means 10911 and then stops. The reason is as follows. It is frequent for the photographer to perform a subsequent release operation after stop of a previous release operation. The above configuration can prevent the vibration detecting means 10091 from being actuated every time in such cases, thereby decreasing the wait time before stabilization of output thereof. When the vibration detecting means 10091 is already started, the vibration detecting means 10091 sends an already-actuated signal to the delay means 10093, thereby shortening the delay time.
FIG. 70 is a flowchart to show the sequential operation when the above operation is processed by a microcomputer, which will be described briefly.
When the camera is powered, the microcomputer first checks the status of the blur correction switch; if the switch is on then the microcomputer will determine whether the release half-depression signal SW1 is generated (#5101.fwdarw.#5102). When the release half-depression signal SW1 is generated, the microcomputer starts the internal timer (#5103). For enabling the photometry, distance-measuring operation, start of deviation detection, and blur correction control by the correction means 10910, the microcomputer releases engagement of the correction means (#5104).
Next, the microcomputer checks whether the counting content in the above timer reaches a predetermined time t1; if not, it will remain at this step before arrival (#5105). This is the process for waiting for the time to stabilize the output from sensor as described previously. When the predetermined time t1 has elapsed, the microcomputer drives the correction means 10910 based on the target value signal to start the blur correction control (#5106).
Next, the microcomputer checks whether the release full-depression signal SW2 is generated or not (#5107). If not, the microcomputer will determine again whether the release half-depression signal SW1 is generated. If the release half-depression signal is not generated either (NO at #5108) the microcomputer will stop the blur correction control and engage the correction means 10910 at the predetermined position (#5111.fwdarw.#5112).
If the release full-depression signal SW2 is not generated but if the release half-depression signal is generated, the operation of steps #5107.fwdarw.#5108.fwdarw.#5107 . . . will be repeated. When the release full-depression signal SW2 is generated in this state (YES at #5107), the exposure operation is carried out onto the film (#5109). Then the microcomputer checks the status of release half-depression signal SW1 (#5110). When the signal becomes off, the microcomputer stops the blur correction control and engages the correction means 10910 at the predetermined position (#5111.fwdarw.#5112).
After the above operation is finished, the microcomputer then resets the above timer once and again starts it (#5113). Then the microcomputer determines whether the release half-depression signal SW1 is again generated within a predetermined time (i.e., within five seconds herein) (#5114.fwdarw.#5115.fwdarw.#5114 . . . ). If the release half-depression signal SW1 is again generated within five seconds after stop of blur correction (YES at #5115), then the microcomputer will perform the photometry, distance-measuring operation, and release of engagement of the correction means 10910 (#5116). Since the deviation detection is still on, the microcomputer immediately performs the drive control of correction means 10910, based on the target value signal (#5106), then repeating the same operation as described above.
Namely, execution of this processing can avoid such inconvenience that the microcomputer actuates the vibration detecting means 10091 and awaits stabilization of output thereof every time the photographer stops the release operation and then restarts the release operation as described above.
On the other hand, when the release half-depression signal SW1 is not generated within five seconds after stop of blur correction (YES at #5114), the microcomputer stops the deviation detection (or stops the drive of vibration detecting means 10091) (#5117). After that, the microcomputer returns to step #5101 to go into the state of waiting for on of the blur correction switch.